1996 sunfire start problems

I have a serious problem with my sunfire. I was driving home last night when my car really bogged down and kep dying on my. By the time i got home my cat was glowing red. today i replaced the cat because i figured maybe it was clogged and it was pretty ripped up from all the heat. well after i replaced it the car still wouldn't start. my next move was to go look at the spark plugs which were just covered in black so i replaced those and tested the coil packs which both went back. And after i replaced the coil packs and the spark plugs i still cannot get my car to run what should i try next because i have already put a considerable amount of money into this problem. Thank you all!